A method for producing a compound of interest utilizing a biocatalyst has advantages that reaction conditions are mild, that the purity of a reaction product is high with a small amount of a by-product, and that a production process can be simplified. Therefore, such a method is used for many compounds to be produced. In the case of production of an amide compound, since nitrile hydratase, which is an enzyme for converting a nitrile compound into an amide compound, was found, biocatalysts have been widely used.
In the industrial utilization of such a biocatalyst, it is important to make efforts toward low cost, energy saving and reduction of environmental burdens.
In order to make efforts toward low cost in the production of an amide compound, for example, the following methods are used: a method in which a microbial cell that highly expresses the nitrile hydratase activity is used in a reaction without being subjected to entrapping immobilization (Patent Document 1); a method of continuous production in which a temperature of a reaction tank downstream is high (Patent Document 2); a method utilizing a plug flow reaction (Patent Document 3); and a method in which the acrylonitrile concentration in an aqueous vehicle at the time of reaction is equal to or higher than the saturating concentration (Patent Document 4).    Patent Document 1 International Publication WO 02/050297 pamphlet    Patent Document 2 International Publication WO 03/00914 pamphlet    Patent Document 3 Japanese Laid-Open Patent Publication No. 2001-340091    Patent Document 4 Japanese Laid-Open Patent Publication No. H11-89575